1. Field of the Invention
The present invention relates to a network device connected to a network, and a control method of the network device.
2. Description of the Related Art
With the progress of computer technologies, a system in which office devices and general household devices which conventionally have only a single function and are not designed to be organically interconnected with each other are connected to other devices across a network and execute common processing is proposed. As techniques which realize this fusion across device networks, protocols such as UPnP (Universal Plug and Play), Jini, and Jxta are known.
UPnP is communication software requiring relatively high-level function processing such as the HTTP technique or XML technique, so it is not easy to always individually develop and install UPnP in each device. Therefore, software of a common communication part of UPnP or the like is generally separately installed in the form of middleware. Also, as the performance of a device having a communication function improves, it is being demanded to install a plurality of middleware programs in a single device. For example, to implement a device having a communication function which can be dynamically found even by Jini in UPnP, two types of corresponding middleware programs must be installed. To cope with various protocols, therefore, a plurality of middleware programs corresponding to the protocols must be installed in a device.
To execute processing by exchanging data between devices while middleware programs corresponding to a plurality of protocols are installed in each device as described above, it is necessary to select devices having middleware programs in which the same protocol is installed. However, the number of installable protocols is limited, and it is impossible to install all the existing protocols in each device. Even if all the existing protocols can be installed in a device, it is impossible to cope with a newly developed protocol. Also, the specifications of each protocol have vague portions, i.e., the specifications are not strictly defined. Therefore, even when the developer of a device has intended to install a protocol completely in accordance with its specifications, ambiguous portions of the specifications of the protocol may produce a difference between interpretations, and this may cause a communication failure between devices.
In addition, a protocol is often installed under conditions not completely complying with its specifications. Furthermore, if a device using a protocol not complying with its specifications is used as a defacto standard, a newly developed device having a protocol complying with the original specifications may not normally communicate with the device using the protocol as the defacto standard. An example of communication failures is a case in which a certain protocol does not distinguish between uppercase letters and lowercase letters, whereas another protocol distinguishes between them. When an XML-related protocol such as SOAP is used, communication may fail due to the presence/absence of a name space.
Installing a plurality of communication middleware programs which are more and more sophisticated, complicated, and enlarged imposes large limitations on the installation environment of a device having a limited computation capability, so efficiently handling this is becoming a serious problem. Japanese Patent Laid-Open No. 8-88672 is one proposal concerning protocol monitoring which finds a difference between protocols in order to ensure communication between devices using these protocols. This reference makes it possible to detect an error of a protocol, and automatically point out the error.
Unfortunately, it is not easy to impart this function to an already shipped device. Also, even when this protocol monitoring is used, it is impossible to cope with all devices existing on the market, so the error detection cannot be well performed. Before purchasing a device, therefore, the user must find a report or the like on, e.g., the Internet to confirm types of devices with which the intended device can communicate.